In a typical communications network a wireless device communicates via a Radio Access Network (RAN) to one or more Core Networks (CNs). The communications network may also be referred to as e.g. a wireless communications network, a wireless communications system, a communications network, a communications system, a network or a system.
The wireless device may be a device by which a subscriber may access services offered by an operator's network and services outside operator's network to which the operator's radio access network and core network provide access, e.g. access to the Internet. The wireless device may be any wireless device, mobile or stationary, enabled to communicate over a radio channel in the communications network, for instance but not limited to e.g. user equipment, mobile phone, smart phone, sensors, meters, vehicles, household appliances, medical appliances, media players, cameras, Machine to Machine (M2M) device or any type of consumer electronic, for instance but not limited to television, radio, lighting arrangements, tablet computer, laptop or Personal Computer (PC). The wireless device may be portable, pocket storable, hand held, computer comprised, or vehicle mounted devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another wireless device or a server.
Wireless devices are enabled to communicate wirelessly within the communications network. The communication may be performed e.g. between two wireless devices, between a wireless device and a regular telephone and/or between the wireless device and a server via the radio access network and possibly one or more core networks and possibly the Internet.
The communications network covers a geographical area which is divided into cell areas. Each cell area is served by a base station. The base station is also referred to as a Radio Base Station (RBS), evolved Node B (eNB), eNodeB, NodeB, B node or Base Transceiver Station (BTS), depending on the technology and terminology used.
An architecture that supports Policy and Charging Control (PCC) functionality is depicted in FIG. 1. This FIG. 1 has been taken from 3GPP TS 23.203 (V.12.0.0) that specifies the PCC functionality for Evolved 3GPP Packet Switched domain, comprising both 3GPP accesses (GERAN/UTRAN/E-UTRAN) and Non-3GPP accesses. The PCC functionality is comprised by the functions of the Policy and Charging Enforcement Function (PCEF) node 101, the Bearer Binding and Event Reporting Function (BBERF) 103, the PCRF node 105, the Application Function (AF) 108, the Traffic Detection Function (TDF) 110, the Online Charging System (OCS) 113, the Offline Charging System (OFCS) 115 and the Subscription Profile Repository (SPR) 118 or the User Data Repository (UDR) (not shown).
PCEF 101 is a functional entity which is responsible for enforcement of policies and charging. The PCEF 101 is located at network node, such as e.g. a Packet data network GateWay (PGW) or a Gateway GPRS Support Node (GGSN), and is therefore referred to as a PCEF node in the following. The PCEF 101 is connected to the PCRF node 105 via a Gx interface. The PCEF 101 encompasses service data flow detection (based on the filters definitions comprised in the PCC rules), as well as online and offline charging interactions (not described here) and policy enforcement. Since the PCEF 101 is the entity handling the bearers it is where the QoS is being enforced for the bearer according to the QoS information coming from the PCRF node 105. This PCEF 101 is located at the Gateway (e.g. GGSN in the General Packet Radio Service (GPRS) case, and PGW in the WLAN case). For the cases where there is PMIP instead of GTP protocol between BBERF 103 and PCEF 101, the bearer control is done in the BBERF 103 instead. The PCEF 101 further has a Gz interface towards the OFCS 115 and a Gy interface towards the OCS 113.
The PCRF 105 is a node which takes decisions regarding policy control and has flow based charging control functionality. The PCRF node 105 provides network control regarding the service data flow detection, gating, Quality of Service (QoS) and flow based charging towards the PCEF node 101. The PCRF node 105 receives session and media related information from the AF 108 and informs AF 108 of traffic plane events. The PCRF node 105 may provision PCC Rules to the PCEF node 101 via the Gx reference point. The PCRF node 105 may inform the PCEF node 101 through the use of PCC rules on the treatment of each service data flow that is under PCC control, in accordance with the PCRF node 105 policy decision(s). The PCRF node 105 determines the PCC rules based on for example information from the AF 108 obtained via the Rx interface, information from the PCEF node 101 via the Gx interface, information from the SPR 118 obtained via the Sp interface and information from the BBERF 103 obtained via the Gxx interface etc. The PCRF node 105 further has an Sd interface towards a TDF 110 and a Sy interface towards the OCS 113.
The AF 108 is an element offering applications in which service is delivered in a different layer (i.e. transport layer) from the one the service has been requested (i.e. signaling layer), the control of Internet Protocol (IP) bearer resources according to what has been negotiated. One example of an AF 108 is the Proxy-Call Server Control Function (P-CSCF) of the IP Multimedia Core Network (IM CN) subsystem. The AF 108 may communicate with the PCRF node 105 to transfer dynamic session information (i.e. description of the media to be delivered in the transport layer). This communication is performed using the Rx interface.
UE-AMBR and APN-AMBR
User Equipment-Aggregated Maximum BitRate (UE-AMBR) is a QoS parameter that represents the aggregated maximum bit rate that may be assigned to a wireless device, such as a User Equipment (UE). This means that the maximum bit rate consumed by all the Packet Data Network (PDN) connections established by a wireless device cannot surpass the UE-AMBR assigned to the wireless device. The UE-AMBR is a QoS parameter defined in the wireless device subscription that is stored in a Home Subscriber Server (HSS) or a Home Location Register (HLR). The HSS is for the third Generation Partnership Project (3GPP) and similar to the HLR which is for a Global System for Mobile Communications (GSM) system. In the following, HSS/HLR is used when referring to either the HSS or the HLR.
The Access Point Name-Aggregated Maximum Bitrate (APN-AMBR) is the aggregated maximum bit rate that may be assigned per Access Point Name (APN) for a wireless device. In other words, the sum of the maximum bit rate of all the PDN connections established by a wireless device towards certain APN cannot surpass the value defined in the APN-AMBR. This QoS parameter is statically defined in wireless device subscription stored in the HSS or HLR but may be dynamically changed by the PCRF node 105.
The PDN connection mentioned above is an association between a wireless device and a PDN. The PDN is identified by an APN and a PDN is accessed via a PGW. The wireless device may have multiple PDN connections. The PDN may also be referred to as an external PDN.
The APN mentioned above is a parameter which identifies the PDN that a wireless device wants to communicate with. In addition to identifying a PDN, an APN may also be used to define the type of service that is provided by the PDN, e.g. connection to Wireless Application Protocol (WAP) server, Multimedia Messaging Service (MMS) etc. APN is used in 3GPP data access networks, e.g. GPRS, Evolved Packet Core (EPC).
The Mobility Management Entity (MME) or the Serving General packet radio service Support Node (SGSN) sends the “used UE-AMBR” to a RAN node, e.g. the eNB or Radio Network Controller (RNC) or Base Station Controller (BSC). The used UE-AMBR is the sum of all APN-AMBR for different PDN connections, restricted to the “subscribed UE-AMBR”, parameter that MME/SGSN receives from the HSS or the HLR at session establishment. The eNB is used in a Long Term Evolution (LTE) network, RNC is used in a Universal Mobile Telecommunications System (UMTS) network and the BSC is used in a GSM network.
This means:Used UE-AMBR=Min[Sum(all authorized APN-AMBR),Subscribed UE-AMBR]
The MME is a network node in the EPC. The MME manages session states, authentication, paging, mobility with 3GPP, 2G and 3G nodes, roaming, and other bearer management functions. The SGSN is a network node which is responsible for delivery of data packets from and to the wireless device within its geographical service area. Its tasks comprise packet routing and transfer, mobility management, logical link management, and authentication and charging functions. The location register of the SGSN stores location information and user profiles of all GPRS users registered with this SGSN. The term SGSN refers to an SGSN which at supports the S4 interface or the Gn and Gp interfaces. S4-SGSN refers to an SGSN which supports the S4 interface and does not support Gn and Gp interfaces. Gn/Gp-SGSN refers to an SGSN which supports the Gn and Gp interfaces and does not support S4 interface. The MME and the SGSN may be separate network nodes or they may be co-located in one network node. In the following, MME/SGSN refers to a co-located MME and SGSN, an MME, a S4-SGSN or a Gn/GP-SGSN.
FIG. 2 illustrates the prior art situation for the UE-AMBR versus the APN-AMBR in a communications network based on LTE. The UE-AMBR limits the maximum bit rate on non-Guaranteed Bit Rate (GBR) traffic for a wireless device 120. The globe in FIG. 2 represents a PDN network, e.g. the Internet.
Step 201
The MME/SGSN 125 receives the subscribed UE-AMBR and subscribed APN-AMBR from the HSS/HLR 116. The MME/SGSN 125 and the HSS/HLR 116 are the network nodes which are informed of and may influence the UE-AMBR.
Step 202
The MME/SGSN 125 sends the subscribed APN-AMBR for a PDN-connection to the GW1 node 130a The GW node also forwards the authorized APN-AMBR to the MME/SGSN 125.
Step 203
The GW1 node 130a, in turn, forwards this to the PCRF node 105. The PCRF node 105 may change the APN-AMBR to a value that is different from the subscribed APN-AMBR for a PDN-connection. The APN-AMBR value for a PDN-connection decided by the PCRF node 105 is referred to as authorized APN-AMBR. The PCRF node 105 sends the authorized APN-AMBR to the GW node 105 for enforcement.
Step 204
The MME/SGSN 125 determines and sends the “used UE-AMBR” to the eNB/RNC/BSC 130 which constitutes the sum of the authorized APN-AMBR for all active PDN connections for one wireless device 120, referred to as APN-AMBR in FIG. 2. However this sum is restricted to the “subscribed UE-AMBR” which the MME/SGSN 125 received from the HSS/HLR 116
Note, that the UE-AMBR is enforced in the eNB/RNC/BSC 130 and the APN-AMBR is enforced in the GW 130. Even though the HSS/HLR 116 and the PCRF 105 have all the APN_AMBR values of all the APNs, only one value is downloaded to the MME/SGSN 125 and the GW 130 per session. The RAN node is the enforcing unit, while the MME/SGSN 125 only computes the used UE-AMBR and sends this to the RAN node.
One problem of the prior art is if the PCRF node 105 decides to change (increase) the APN-AMBR value for a specific PDN connection it may potentially have no effect. Since the used UE-AMBR is restricted by the subscribed UE-AMBR this means that an APN-AMBR that is increased beyond this value will have no effect at all on maximal throughput. Of course this is not a problem in cases where the UE-AMBR value specified by the HSS/HLR 116 is very high (which in the extreme case implies that UE-AMBR is disabled in practice).
Another problem is that when, for example, an operator may want to allow simultaneous access to multiple PDNs (e.g. Internet access and virtual private network (VPN)-connectivity) with a fair usage policy that applies across the APNs. Before the usage limit is reached the UE-AMBR should be set to the sum of the APN-AMBR of all active PDN-connection, thus allowing for full speed on all PDN-connections at the same time. The full speed on all PDN-connections will continue for the rest of the time, even though it may not be necessary. This may be described as the operator may want to restrict this full speed upon certain conditions, e.g., when the usage limit established in the user subscription is surpassed. E.g. a user has a subscription that provides 1 Mbps for each of the access sessions (UE-AMBR=numberOfSessions*1 Mbps), up to 1 Gb per month. If the volume consumed surpasses the 1 Gb, then the user will still be able to open sessions but the bitrate of all the simultaneous access sessions will be restricted to 128 Kbps (UE-AMBR=128). When the usage limit is reached the UE-AMBR should be set to a value that is lower than the sum of the APN-AMBR of all active PDN-connections. The PCRF node 105 can retrieve information on data usage, but in the present standard has no influence on the used UE-AMBR decided by the MME/SGSN 125.